In order to increase mobility of electronic devices, designers are challenged to figure out how to reduce sizes and weights of the electronic devices. On a portable device, the size is a critical issue for the designer. A portable device (e.g., smart phones, digital cameras, sports cameras, tablets, or similar handheld devices) has less space for disposing buttons for different functions.
If the portable device has ten different functions and each of the functions requires an individual button to manipulate (e.g., trigger, control, configure, etc), the portable device must has at least ten individual buttons. In this case, each of the ten buttons will be small, hard to locate and easy to be damaged. On the other hand, the size of the portable device must be enlarged for accommodating these buttons. It is a dilemma between increasing the mobility or the maneuverability of the portable device. However, the cutting-edge portable device must be capable to fulfill many functions within a compact size.